The present disclosure relates to non-contact position sensing devices and methods for sensing a position of an object without contact.
In recent years, information terminals and miniature TV terminals, such as personal digital assistants (PDAs), smart phones, tablet PCs, and vehicle navigation systems, etc. have been widely used. Many of such terminals employ a touch input portion in order to increase operability. For example, the touch input portion is formed of a display for displaying screen components such as icons, etc. of a graphical user interface (GUI), and the display is configured to receive input of information when a display screen is touched by a stylus (a touch pen) or a finger. On a display screen of the display, for example, a plurality of screen components such as ions, etc. are displayed, and a user touches the display screen by a stylus or a finger to select an icon, thereby starting an application program assigned to the icon.
As a technique other than the touch input portion, non-contact position sensing techniques using a plurality of infrared LEDs and photosensors have been known. For example, according to a technique disclosed in Japanese Patent Publication No. H7-200143, an infrared light ray with a modulated light intensity is output from a predetermined position, a reflected light ray from an object such as a stylus or user's finger, etc. is received, and a position of the object is detected based on a phase difference between the output light ray and the reflected light ray.